Method and apparatus for dehydrating petroleum



June 15, 1937. H. c. EDDY 2,083,801

. METHOD AND APPARATUS FOR DEHYDRATING PETROLEUM Filed Sept. 6, 1932 2Sheets-Sheet l [usual [was] EMuQs ION 1'21 EmuusmN F 2.

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BNUkSAON M H. C. EDDY June 15, 1937.

METHOD AND APPARATUS FOR DEHYDRATING PETROLEUM 2 Sheets-Sheet 2 FiledSept. 6, 1932 [/v 1/5/v roe.- HHEOLO. 6. 600),

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HTTOBNEJM Patented June 15, 1937 UNITED STATES PATENT OFFICE METHOD ANDAPPARATUS FOR DEHY- DRATING PETROLEUM Application September 6, 1932,Serial No. 631,785

16 Claims.

My invention relates to a novel method of electrically treatingemulsions to separate these emulsions into their constituent phases andto an apparatus of novel character for efiecting this treatment. Theinvention is particularly applicable to the treatment of petroleumemulsions, and it is in this capacity that the preferred embodiment willbe described, though it should be understood that the utility of theprocess and apparatus is not limited to this type of emulsion.

Petroleum emulsions are essentially of two types,--(1) the type having acontinuous phase of oil in which particles of water are suspended,usually termed a water-in-oil emulsion, and (2) the type having acontinuous phase of water in which minute oil particles are suspended,usuallytermed an oil-in-water emulsion. The present invention isapplicable in both types.

With regard to emulsions of the first type in which the oil is thecontinuous phase, one conventional method of separating these phases isto subject the emulsion to the action of a high potential electricfield, usually of alternating character. In such a field the dispersedparticles are coalesced into droplets of suilicient size to gravitatefrom the oil. This coalescence is, however, retarded by the viscosity ofthe oil forming the continuous phase, it being clear that before twodispersed particles can coalesce, they must be moved at least a shortdistance through the oil. I have found that the action of coalescencecan be greatly facilitated if the emulsion particles are suspended in amedium of less viscous character than the oil. In the preferredembodiment of the invention it is preferable to position the particlesto be coalesced in a gaseous phase.

In the second type of emulsion the external phase may be formed of abody of conducting liquid such as water. Electrical treatment of such anemulsion has heretofore been impossible in view of 'the fact that thewater phase bridges between the electrodes and in effect short circuitsthe electrodes to such an extent as to prevent a building up ofpotential difference requisite to electric treatment. I have found thatthis type of emulsion may be treated by subdividing the emulsion intorather minute particles which are separated from each other by a gas,these minute particles and the gas being subjected to an electric fieldwhereby coalescence takes place. Thus, the material between theelectrodes is-essentially a gas with minute particles suspended therein,and although certain of these particles are conducting, the gas preventsexcessive current flow.

It is an object of the present invention to electrically treat anemulsion by subdividing this emulsion into minute liquid particlesseparated from each other by a gas, and to subject these minuteparticles to the action of an electric field. The gas acts as adielectric barrier to prevent excessive current flow between theelectrodes, and at the same time furnishes a low-viscosity medium whichdoes not unduly retard the movement of the particles therethrough.

It is a further object of the invention to suspend such minute liquidparticles in a gaseous atmosphere and to establish an electric field ofsufiicient intensity to ionize the gas. It is usually impossible tomaintain voltage gradients sufliciently high to ionize any, portion ofthe. space between the electrodes when'this space is filled with acontinuous phase of oil in which emulsion particles are suspended. If,however, a gaseous medium is substituted for the continuous phase ofliquid, this ionization can be readily established and apparently has avery desirable action on the emulsion particles thus suspended in theionized gas.

I have found that very satisfactory results are obtained by atomizingthe emulsion, and it is an important object of this invention to providea method and apparatus whereby emulsions are electrically treated bybeing introduced into an electric field in an atomized state.

This atomization maybe efl'ected by any one of a number of means. Onemethod of atomizing such an emulsion is by the use of an atomizer of themechanical type. Suchatomizers are often used in conjunction withfuel-supply systems of oil-burning boilers. In such an atomizing systemthe liquid is broken up by centrifugal or mechanical forces without theuse of a high velocity jet of air or other gas.

It is an object of the Present invention to minutely subdivide theemulsion into an atomized state and to introduce this atomized emulsioninto a gas-filled electric field.

Another type of atomizing system which can be very successfully used inconjunction with the present invention atomizes the emulsion by the umof a jet of gas delivered to the device under pressure. ordinarily movedinto contact with a stream of the emulsion in such a manner thatatomization takes place, the material issuing from the atomizercomprising a high velocity mixture of minute emulsion particles in agaseous atmosphere.

It is an object of the present invention to utilize a stream of gas foratomizing the emul- A high velocity stream of the gas is sion, and tointroduce the gas and the atomized emulsion into an electric field.

A further object of the invention is to atomize the emulsion by forcingthis emulsion under high pressure through small orifices so designed asto effect atomization.

One well-known type of petroleum emulsion, when viewed under amicroscope, discloses an emulsion in which the oil is the continuousphase and in which the dispersed phase comprises a large number ofemulsion particles, each emulsion particle being formed of an emulsionof the oil-in-water or water-in-oil type, the latter type of emulsionpredominating. This physical setup can be found in both loose emulsionsand in the fine-grained, tight emulsions, even the extremely minutedispersed particles being composed of an emulsion of oil and water. Itis sometimes desirable to regulate the atomizing process so that theminute particles expelled from the atomizing device will be smaller thanthe often results in the formation of a mixture which is much moresusceptible of electric treatment f'than was the original emulsion, andit is another object of the invention to provide a method and apparatusutilizing this mode of operation wherein new interfaces are formed bysuch subdivision.

While it is usually desirable to atomize the incoming emulsion and thussecure a maximum effect from the ionization of the gas, this is notalways necessary. In one embodiment of the invention a sheet of theemulsion is moved into the electric field inf'spaced relationship witheach of the electrodes, this emulsion being separated from eachelectrode by a body of gas. If a suificient potential is maintainedbetween the electrodes,

, this gas will be ionized on each side of the emulsion, thusapproaching the desirable action which takes place if the emulsion iscompletely atomized.

It is a further object of the invention to provide a method andapparatus for treating an emulsion by the use of an electric field setup between two electrodes, the emulsion being introduced into this fieldin spaced relationship with the electrodes and being separated fromthese electrodes by an-ionized gas.

Further objects of the invention lie in a system tion of Fig. 2 andillustrates the atomizing system.

Figs. 4, 5, and 6 are diagrammatic views illustrating alternative formsof the invention.

Fig. 7 is a view taken on the line 1-.'| of Fig. 6.

Referring particularly to Fig. i, I have illustrated a dehydrator tankIn of conventional construction and including a lower head H and anupper head 12. The interior of this tank is partially filled with a bodyof liquid I3, the interior of the tank above this body of liquid beingfilled with a body of gas. A conventional gauge l5 may be used toindicate the level of the body of liquid l3.

Suitable electrodes are provided in the upper portion of the tank ill toset up an electric field therein. In the form of the invention shown inFig. 1, this electrode system comprises a central live electrode [8supported by an insulator I3, and an outer live electrode 20 supportedby an insulator 2 I. Other types of electrode structures may, however,be utilized without departing from the spirit of the invention. Asshown, the central and outer live electrodes [8 and 20 cooperate indefining a treating space 22 which is open at its upper and lower ends.If desired, plates 23 may be positioned on the central live electrode l8so as to concentrate the discharge from the edges thereof. These platesare not, however, essential to the operation of the invention.

An electric field is set up in the treating space 22 by a suitablesource. In Fig. 1 this source takes the form of two transformers 24 and25. A secondary winding 26 of the transformer 24 is connected to thetank It] and to the central live electrode l8, this tank being groundedas indicated by the numeral 21. In addition, a secondary winding 28 ofthe transformer 25 is connected to the tank and to the outer liveelectrode 20. It is preferable that the secondary windings 26 and 28 beconnected in additive relation so that the potential between the centrallive electrode I 8 and the outer live electrode 20 will be much greaterthan the potential between either of these electrodes and the tank. Sucha system thus offers a convenient means for establishing electric fieldsof extremely high gradient without requiring the use of large andexpensive insulators.

The emulsion is introduced into the treating space 22 by an atomizingmeans 30. The gas and the emulsion are supplied in intermixed state tothe atomizing means 30 through a pipe 3| which communicates with thedischarge of a pump 22, diagrammatically shown. Emulsion is supplied tothe intake of this pump through a pipe 33 including a valve 34, whilegas is supplied thereto through a pipe 35 including a branch 36communicating with an external source of gas. A valve 31 controls theflow of such gas through the pipe 36. A pipe 38 communicates between theupper end of the tank In and the pipe 35 and includes a valve 39 forcontrolling the flow of gas recirculated from the upper end of the tankand into the intake of the pump 32. A major portion of the gas utilizedmay be gas which is thus recirculated, only sumcient gas being suppliedthrough the pipe 36 to compensate for losses in the system.

In the form of the invention shown in Fig. 1,

4 the atomizing means 30 is shown as comprising an annular pipe 4|communicating with the pipe This annular pipe provides a plurality ofatomizers 42 which may be of any well known type and which minutelysubdivide the emulsion into an atomized state, discharging this emulsiondownwardlyin the treating space 22. In some instances it is possible toutilize atomizers 42 in the form of suitably designed nipples whichreceive the intermixture of gas and emulsion, the gas assisting inatomizing the emulsion as it moves through these nipples.

In the operation of this form of the invention the atomized emulsionand, the gas discharged from the atomizers 42 moves downwardly in thetreating space 22 and is subjected to the action of the electric fieldtherein. This field has two rather distinct tendencies. In the firstplace, it will be clear that if each minute emulsion particle containsboth oil and water, the microscopic dispersed particles in this emulsionparticle will be acted upon by the electric field and will tend tocoalesce without necessarily moving from the emulsion particle. In thesecond place, the electric field will tend to coalesce adjacent emulsionparticles, as well as to act upon the emulsion comprising theseparticles. Thus the treating action is a dual one,the internal structureof each emulsion particle is changed, and adjacent emulsion particlesare coalesced.

The coalescence of adjacent emulsion particles takes place morereadilythan the coalescence of dispersed particles of oil which may bein the field. Thus, if there are present in the field threeconstituents, namely, gas, minute particles of oil, and minute emulsionparticles, more of the emulsion particles will be coalesced than the oilparticles. This is due primarily to the difference in dielectricqualities of the constituents, it having been found that thepredominating coalescence is between the particles of differentdielectric strength. The dielectric strength of the gas and oilparticles is of the same order of magnitude, but the dielectric strengthof the emulsion particles is quite different from that of the gas. Itfollows that the major action taking place in the field will be acoalescence of emulsion particles rather than oil particles.

The coalesced material drops downward to the body of liquid l3. Ifdesired, the coalesced constituents may be allowed to settle in thebottom of the tank ID, as will be hereinafter set forth. In the form ofthe invention shown in Fig. 1, however, these constituents are removedfrom the tank ill before any material stratification takesplace. This isaccomplished by withdrawing the liquid through a pipe 45 whichdischarges into a settling tank 46 through a spray pipe 41 in the usualmanner. The oil and water stratify in the tank 46, the oil rising to theupper end and being withdrawn through a pipe 48, while the water dropsto the lower end of the tank and is withdrawn through a pipe 49. It willbe apparent that the gas separates from the liquid in the upper portionof the tank Hi, this gas being withdrawn through the pipe 38 andrecycled, as previously set forth.

Another type of atomizing system is .disclosed in Figs. 2' and 3. Here apipe 52 recycles gas from the upper portion of the tank to the intake ofa pump 53, a pipe 54 delivering a new supply of gas to the pump tocompensate for losses in the system.- The pump .53 may be of any desiredtype which will greatly increase the pressure on this gas, this pumpdischarging into a T 55 and into an annular space 56 between an outerpipe 51 and an inner pipe 58 extending downward from this T. The upperend of the T 55 is closed by a plug 59 so that the gas is forceddownward in the annular space 56. This gas enters a manifold chamber 60formed between an outer annular pipe 6| and an inner annular pipe 62.This manifold chamber distributes the gas to a plurality of nipples 63.A nozzle 64 extends down-' ward in each nipple and cooperates therewithin defining a discharge space 65-through which the gas passes at highvelocity. The nozzles 64 terminate short of the ends of the nipples 63and communicate with the interior of the inner annular pipe 62, whichforms a manifold chamber 61 for supplying emulsion thereto. Emulsion issupplied to the chamber 61 through the pipe 58 by a pump 69 shown inFig. 2. An electrode sysf tern similar to that shown in Fig. 1 isutilized.

The gas is usually delivered to the manifold chamber 60 at a pressuresubstantially greater manner previously described. In some instancesthepump 69 can be dispensed with, the fastmoving jet of gas flowing throughthe discharge space 65 acting to draw the emulsion through the pipe 58.

In Fig. 4 I have illustrated a treater similar to that shown in Fig. 1but equipped-with a different type of atomizing means indicated ingeneral by the numeral 10. This means takes the form of an annular pipeH communicating with the discharge of a pump I2 which supplies emulsionthereto under pressure. Positioned on this pipe H and communicatingtherewith are a plurality of atomizers I3 of the mechanical orcentrifugal type. Such atomizers are well known in other arts and act tobreak up the emulsion into a mist or spray either by mechanicallyagitating the emulsion or by impinging a high velocity jet of theemulsion on a stationary or moving body. Atomizers of the centrifugaltype wherein the emulsion is subjected to a whirlingaction to effectatomization may also be utilized.

It will be noted that in this form of the invention the atomizedemulsion moves upward through the treating space. Two modes of operationare possible. The atomized emulsion maybe forced upward into thetreating space at such a velocity that it will not drop therein underthe action of gravity but will move from the upper end thereof anddownward around the outer live electrode indicated by the numeral. 15.On the other hand,

be supplied through a pipe 16 controlled by a' valve TI. Sometimes acertain amount of gas is generated during treatment, and any excess gascan be withdrawn through a pipe 18 controlled by a valve 19.

In Fig. 5 still another form of the invention isv disclosed. Here asingle live electrode 80 in the form of a sleeve is utilized, thissleeve being supported by an insulator 8|. A transformer 82- supplieshigh potential current to this electrode through a conductor 83, thistransformer being tric field between the tank and the electrode 80.

also connected to a tank 84 to set up an elec- The main treating spaceis, however, formed inside the electrode 80 and is indicated by thenumeral 85. An inner grounded electrode 86- cooperates with theelectrode 80 in defining this main treating space. In this form of theinvention the electrode 86 is in the form of apipe which receivesemulsion under-pressure from a pump 88, the pipe providing a pluralityof atomiz- The desirable action between the ionized gas and v ing meansfor atomizing the emulsion and introducing it into the treating space85. Any suitable atomizing means may be utilized. In the form shown inFig. 5 I provide a plurality of orifices 89 which atomize the emulsionas it moves therethrough. Whether. orifices 89 are utilized in thiscapacity or whether other v ypes of atomizing means are utilized, it isdesirable to so position these atomizing means that they discharge intothe treating space in an upwardly inclined direction. If these meansdischarge radially outward, the atomized emulsion will drop downward inthe treating space 85. If, however, these means are inclined upward, thespeed .of movement of the subdivided emulsion through the treatin space85 can be controlled by the amount of inclination. If the atomizingmeans are sufilciently inclined, it is possible to reverse the fiow ofthe subdivided emulsion through the space 85 and move this emulsionupward therethrough. In. this event the. treated particles will movedownward between the tank 84 and the-electrode 80 and will be subjectedto a further electric treatment therein.

The treated emulsion moves downward through the body of gas in the upperend of the tank 84 and enters the body of liquid in the lower end ofthis tank. In the form shown in Fig. 5 this body of liquid comprisesstratified bodies of oil and water indicated respectively by'thenumerals 90 and ill. The constituents of the treated emulsion thusstratify and enter these bodies of oil and water. The oil may becontinuously withdrawntreating space. Contact between this ionized gasand the emulsion usually facilitates treatment,

though it should not be understood thatlt is always necessary to utilizeionizing potentials.

the emulsion can be obtained without atomization, though usually to aless effective degree. In the form of the invention shown in Fig. 6 theincoming emulsion is contacted on two sides by the ionized gas, ratherthan being subdivided into minute particles each of which is completelysurrounded by the gas. One mode of effecting this end isto introduce theemulsion through a pipe 108 communicating with an annular discharge pipe.illl. An annular slot is cut in the lower face of the pipe IOI, thisslot communicating with an annular discharge opening I02 formed betweena pair of concentric rings secured to the annular pipe NH. The result isthat an annular jet of the emulsion is moved downward through the gas inthe treating space in spaced relationship with the electrodes so that abody of gas is positioned on each side of this emulsion and separatesthe emulsion from the adjacent electrode surface. Any suitableelectrodes may be utilized, but in the preferred embodiment it isdesirable to utilize an electrode system such as shown in Fig. l theinnerand outer electrodes being indicated by the numerals Ill andllliand being insulated from the'tank to define the treating space, theemulsion introduction system being grounded to the tank. The treatedconstituents can be removed-from from. the tank it will be clear that nodanger of explosion exists when natural gas is utilized.

' Other gases may, however, be substituted and,

if desired, may be wholly or partially inert. They should be of suchcharacter that they are substantially non-condensable at the temperatureexisting in the treater; otherwise condensation will take place and thecondensate may unite with the body of liquid in the lower portion of thetank and thus fail to maintain the gaseous atmosphere in the upperportion of the tank.

I claim as my invention:

1. A method of electrically treating an emulsion, which method includesthe steps of: subdividing substantially the entire quantity of saidemulsion to be treated to form a plurality of minute particlespositioned in a gaseous atmosphere; and subjecting the gaseousatmosphere and said minute particles positioned therein to an electricfield of suflicient intensity to coalesce the dispersed phase liquid ofsaid emulsion; and separating the coalesced phase liquid from the liquidforming the continuous phase of said emulsion. I

2. A method of treating an emulsion composed of a continuous phase ofoil and a dispersed phase formed of emulsion particles of emulsified oiland water,'which method includes the steps of: atomizing said emulsionto formminuteoil particles and minute emulsion particles each emulsionparticlecontaining emulsified oil and water and being of smaller sizethan the emulsion particles in the original emulsion,-each of the minuteemulsion particles and the minute minute droplets are agglomerated;separating said gas from said agglomerated droplets; and recycling theseparated gas into the incoming emulsion.

4. A method of treating an emulsion by the use of a pair of electrodesdefining a treating space, which method includes the steps ofmaintaining in said treating space a gas; impressing a poten- .tialdifference between said electrodes sufllcient to ionize said gas;introducing said emulsion in a subdivided state into the ionized gas;and subsequently separating the constituents of said emulsion from eachother and from said gas.

5. A method of electrically treating an emulsion, which method includesthe steps of bringing a high-.velocity jet of gas in contact with aflowing stream of said emulsion to atomize said emulsion; introducingboth said gas and the atomized emulsion into an electric field; and

subsequently separating the constituents of said emulsion and said gas.

6. A method of treating an emulsion by the use of a pair of electrodesspaced from each other to define a treating space, which method includesthe steps of: maintaining said treating space filled with a gas;introducing a stream of the emulsion to be treated into said treatingspace in and the emulsion to be treated to said atomizing means, saidgas atomizing said emulsion and being discharged from said orifice alongwith the atomized emulsion; a tank into the upper end of which saidorifice of said atomizingmeans discharges, said upper end of said tankcontaining a body of gas and the lower end of said tank containing abody of liquid; means for setting up an electric field in the gas in theupper end of said tank, the constituents discharged from said atomizingmeans moving into said electric field; means for withdrawing theemulsion constituents from said tank; and means for withdrawing from theupper end of said tank an .amount of gas substantially corresponding tothe gas introduced into said tank with said emulsion. 8; A combinationas defined in claim 7 in which said last-named means includes a pumpmeans for withdrawing gas from-the upper end of said tank and recyclingthe gas thus removed into said atomizing means.

9. A method of electrically treating an emulsion of the oil-in-watertype, which method includes the steps of: setting up an intense electricfield between a pair of electrodes; atomizing said emulsion to break thewater.phase into minute water particles suspended in a gas; subjectingsaid gas and said atomized emulsion to the action of said electricfield, said gas preventing bridging of said electrodes by said waterparticles; and separating the phases of said emulsion.

10. A method of electrically treating an emulsion to cause separation ofthe constituent phase liquids thereof, which method includes the stepsof: substantially filling a treating space with a gaseous atmosphere inwhich is suspended atomized particles of the raw emulsion to be treated,said atomized particles being separated by gas; establishing in saidtreating space an electric field of sufiicient intensity to ionize saidgas and treat said atomized'particles of said emulsion; and separatingthe treated phase liquids or said emulsionfrom each other and from saidgas.

11. A method of electrically treating an emulsion to cause separation ofthe constituent phase liquids thereof by the use of a restrictedorifice, which method includes the steps of: atomizing said emulsion bymoving a stream thereof through and from said restricted orifice tosubdivide same into minute masses spaced from each other; in-

troducing the atomized emulsion into an electric field containing agaseous atmosphere whereby said minute masses are separated from eachother by the gaseous atmosphere in said field, said electric field beingof sufiicient intensity to treat said masses; and separating -thetreated phase liquids of. the treated emulsion from each other and fromthe gas forming said gaseous atmosphere. l

12. A methodof electrically treating an emulsion to cause separation ofthe constituent phase liquids thereof, which method includes the stepsof: moving a stream of emulsion upward in a treating space; atomizingall of the emulsion contained in said stream to form a gaseousatmosphere in which is positioned the atomized masses of theemulsion;.subjecting the gaseous atmosphere and its contained atomizedmasses of emulsion'to the action of an electric field in said treatingspace; and separating the treated phase liquids of said emulsion fromeach other and from the gas of said gaseous atmosphere.

13. A method of electrically treating an emulsion to cause separation ofthe constituent phase liquids thereof, which method includes the stepsof moving into a treating space a stream of gas carrying minute dropletsof emulsion; establishing an electric field in said treating space ofsufiicient intensity to coalesce said minute droplets; first separatingthe gas from the treated phase liquids; and then collecting andseparating the treated phase liquids of said emulsion-from each other.

14. In combination in an electric treater for emulsions: .a pair ofelectrodes defining a treating space containing gas; means for settingup an electric field between said electrodes; an atomizing meansproviding an emulsion passage and a arating same moving'from saidatomizing means into said electric field.

15. A method of treating an emulsion of oil and water by use of twovertically-extending electrodes bounding a treating space, which methodincludes the steps of: moving a stream of emulsion downward insaidtreating space between said electrodes; maintaining a body of gas onopposite sides of said stream between said stream and said electrodes;establishing an electric field in said treating space-to act upon thedownwardmoving stream; and separating the constituents of the treatedemulsion in a zone exterior of said treating space containing said gas.

16. In combination in an electric treater for I emulsionsi a pair ofelectrodes defining a treating space containing gas; means for settingup an electric field between said electrodes; a highvelocity-dischargeatomizing means discharging into said electric field and capable ofbreaking up emulsion delivered thereto into minute masses which aredischarged into said field, said atomizing means including an orificedischarging into said electric field; means for supplying the emulsionto be treated to said atomizing means; and means for delivering gasunder pressure to said atomizing means, said atomizing means subdividingsaid emulsion and discharging the subdivided emulsion along with saidgas through said orifice and into said field.

HAROLD C. EDDY.

